Guide for Electret Condenser Microphones
ELECTRET CONDENSER MICROPHONE (ECM)
A microphone as an audio-electric converting device, whose
audio pickup section has a structure of a condenser consisting of
a diaphragm and a back plate opposite thereto, is called a
condenser microphone.
The motion of the diaphragm by sound is picked up as a variation
of capacitance between the diaphragm and the back plate.
In this case, usually, a voltage of tens or hundreds of volts should
be applied extermally as a condenser polarizing voltage.
However, electric charge can be maintained in a polymer film by
the electret effect, thereby eliminating the polarizing direct-current
high voltage. Such is an electret condenser microphone.
In structure, electret condenser microphones are grouped into the
following three types according to where the electret film is used:
qFoil-type electret condenser microphone
The diaphragm itself is made of an electret polymer film.
wBack-type electret condenser microphone
Contrary to q, a polymer film is adhered to the back plate.
eFront-type electret condenser microphone
The back plate is structurally eliminated. The diaphragm and the
inside portion of the microphone capsule itself form the
condenser. The electret is located inside the case.
Structural schema of Electret Condenser Microphone
Cloth
Diaphragm
Ring
Spacer
Back Plate
Capsule
IC
(FET)
PC Board
Holder
Terminology
Sensitivity
The sensitivity is defined as the output voltage for a specified
acoustic stimulus and load condition. In this catalog it is expressed
in dBV/pa (dBV/10µbar).
In the case of dynamic types it is expressed as the open circuit
voltage appearing at the output terminals.
In the case of electret type it is expressed with a specified resistive
load and supply voltage since the output resistance tends towards
constant current characteristic.
Output impedance
The output impedance represents the internal electric resistance
within a microphone as seen from the side of output terminals of the
microphone.
JIS C-5502 specifies 50,200,250,400 and 600 ohms as standard.
In the case of ECMs, the effective output resistance is determined
mainly by the valve of load resistance. It can be made higher or
lower by the value of load resistance with a corresponding change
in sensitivity.
Frequency Response
The frequency response of a microphone is the data indicating
which frequency range, from the lower to the higher range, the
microphone has a certain sensitivity. In other words, it is the
frequency range within whitch the microphone can receive sound. It
is expressed as 50 Hz-15000 Hz.
Electret Condenser Microphones Specifications Table
Omnidirectional
Dimensions
Model No.
KUF4723
KUR0023
KUF4623
KUF4523
KUB4323
KUF4323
KUB4223
KUB3323
KUF3323
KUB2823
KUC3523
KUC2123
KUC4023
Diameter Height
(mm) (mm)
4.0
4.0
6.0
6.0
6.0
6.0
6.0
6.0
6.0
6.0
9.4
9.4
9.7
0.9
1.5
1.0
1.2
1.5
1.5
1.9
2.2
2.2
2.7
4.5
6.5
6.7
Mass
(g)
0.04
0.08
0.1
0.1
0.15
0.15
0.15
0.2
0.2
0.2
0.6
0.8
0.9
Terminal Style Chip-Condenser
Current
Sensitivity Impedance Standard Power
Supply
Consumption
(dB/Pa)
(kΩ)
(mA)
(V DC)
–45
–45
–45
–45
–44
–45
–40
–45
–45
–45
–45
–45
–45
2.2
2.2
2.2
2.2
2.2
2.2
2.2
2.2
2.2
2.2
1.0
1.0
1.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
4.5
4.5
4.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.8
0.8
0.8
Lead
Wire
Type
PCB Solderless Built-In Soldered
is
Type available available
Type
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Page
No.
3
3
4
4
4
5
5
5
6
6
6
7
7
Unidirectional
Dimensions
Model No.
KUB8223
KUB8023
KUC8323
Diameter Height
(mm) (mm)
8.0
9.4
9.4
4.7
6.5
6.5
Mass
(g)
0.5
1.0
0.8
Terminal Style Chip-Condenser
Standard Power
Current
Sensitivity
Supply
Consumption
Impedance
(dB/Pa)
(mA)
(V DC)
(kΩ)
–45
–45
–45
1.0
1.0
1.0
4.5
4.5
4.5
0.5
0.8
0.8
Lead
Wire
Type
PCB Solderless Built-In Soldered
is
Type available available
Type
●
●
●
※ KUC: ﾎｲﾙｴﾚｸﾄﾚｯﾄ / Foil Electret KUB: ﾊﾞｯｸｴﾚｸﾄﾚｯﾄ / Back Electret KUF: ﾌﾛﾝﾄｴﾚｸﾄﾚｯﾄ / Front Electret
●
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Page
No.
8
8
8
Electret Condenser Microphones
(Omnidirectional)
Unit: mm
KUC2123
PCB Type
6.5
2
4.5
1 μF
1
OUTPUT
1
φ9.4
IC
2.54
0.4
Lead Wire Type
EARTH −
2
2
;;; ;;
;;; ;;;
6.5
1
φ9.4
POWER SUPPLY +
1 kΩ
2
MIC.CASE
20
dB
10
0
-10
-20
-30
50
100
200 Hz
500
1k
2k
Hz
5k
10k
20k
KUC4023
PCB Type
6.7
2
4.5
1 μF
2
IC
OUTPUT
POWER SUPPLY +
1 kΩ
2.54
0.4
φ9.7
1
1
EARTH −
2
MIC.CASE
φ9.7
Lead Wire Type
;;
;
6.7
;;
;;
;;
2
20
dB
10
0
-10
1
-20
-30
50
100
200 Hz
500
1k
2k
Hz
5k
10k
20k